Trigger-pull measuring device



Nov. 28, 1944. s. T. NQVAK` 42,363,541

TRIGGER-PULL MEASURING DEVICE Filed Nav. 14. 1942 E tephen T- Nrn/ak 3,43 vlt;

Patented Nov. 28, 1944 N N imi'rliD STATE S PATE NT QFFICE 'rnrGGEn-rULL MEAsURING DEVICE e l Stephen T.` Novak, Dayton, Ohio f `ApeliieatiehNetemher14,1942, serie1Ne.465,56s f comme, (c1. 7s-fieri flammea underline eet ef March a, V188s, as amenaeanprilso, ischemia-@751i f The invention described herein may be manufactured and used by or for the Government for ,e governmental purposes, withoutI the paymentto l me of any royalty thereon. f l

This invention relatesto a device for measuring the force (in pounds) i necessary to operate the trigger of rearms (triggerepull) a The object of invention is to provide a `trigger-pull measuring device which will be relativelyinexpensive to construct, vwhich will be adaptable for production measuring and which may be operated by `unskilledoperators." For the `attainment of these and` suchother objects asmay hereinappear or be pointedhoutI have shown an embodiment of i, myinvention in the accompanying drawing.

` The i'lrearm to be tested, in the illustration, a` riile, is held"firmly `against recoil between two l stops I and 2. "At the ngerside of the trigger e is adjusted one end (the right,\as seen in the e figure) of a slide bar 4, which is guided by a stud the', parts continues until the gunfires. h Toemeasure the air pressure required to pull the gun triggera pressure gauge I is connected to the branch outlet'ofTI'I. l

To permita reading of the maximum pressure reachedgby gauge l; (which is the trigger-pullin pounds)the following arrangement is provided to maintain the said maximum reading (trigger-` pulir). rhevaive I4, which is inthe suppiyhne tothe beuews'ehember (as already described),

" has a piston 2I lconnected byrod` 22 to the lever arm 5. `Whenthe air pressure in bellows cylinder I `I has reached a pressure to turn lever arm 3xed to the machine `frame, and received in` l lever 5 `pivotally mounted in a dependent-position suiliciently tothe left; the further leftwardmovementof the lever,` arm` permitted by the sudden release of resistance presented bythe trigger will pull rod 22 and its piston 2| to a position shutting e offxfurther `air pressureto the chamber II, After the maximum reading of gauge; 'I has` been noted, the air `pressure in the system is released bymoving link 20 in a direction to shut inlet `valve `I5 and to open outletfvalve Ito `exhaust; the gang valves are held in this position until the air `pressure in the system'has been re- Y leased;` `The parts arey returned rightwardly by a spring 5s one end of which is secured to lever 5 and` theother anchored to the `machineframe.

tionof air` pressure in its chamber II,` to force bellows rod I2 to the left; rod I2 isarticulated to the said lever arm 5. Air pressure is conducted from a source of air pressure I6through a control valve I5, a second valve I4 and pipe T I3 (more particularly, the line direction thereof), to the bellows chamber II. The branch outlet of T I3 is connected, through the line direction of a second T I'I, to a control valve I8 which is `connecter/itc exhaust I9. j

Valves I5 and I8 are operated together, as gang valves by means of a link 20. Gang valves I5,` I8 are so arranged, and connected by link 20,- that when `one is opened, the otheris closed and vice versa.` After the firearm to be tested is placed against stops `I and 2, as already explained, the link 20 is moved, by means of a handle 20h thereon, in position to open gangvalve I5 and to close gang valve I8 (toexhaust I9). The air pressure, conducted to bellows `chamber II (as traced above), forces lever 5 leftward, the latter pulling bar 4 in that direction. Leftward movement of To check the calibration of the gauge apulleyi" weight is connected by a cord `3i to the end` of bar 4, a's `shown indot-and-dash lines in the gure.` :The reading taken when theair pressure just starts to; pull the `weights is checked against the Calibrating weights. h i i Iclaim:` ,3 e Y 1. In a, device for measuring the trigger-pull of `firearms, the combination of means for holding "the rearm, a lever pivotallymounted at one end and provided with a spring urging it in` one direction, abar articulated to the distal end of the said lever and mounted for an extent of slid-` ing movement, a `pin provided at the distal end of the `said bar and adapted to be placed in abutting relation to the trigger of the irearm a bellows having a rod `articulated to the said lever and adapted to turn the lever in a direction opposite to the said spring-urged direction, a source of air pressure, an inlet valve leading to the said source, an exhaust outletvalve leading to the atmosphere, a common gang control for the said two valves, pipe means connecting each ofthe l said two valves to the said be1lows,`a pressure gauge inthe said pipe connection between the bellows and the exhaust outlet valve, and a shut-` `oif valvein the said pipe connection between the bellows and the inlet valve provided with a piston rod articulated to the lsaid lever adapted, when the pressure inthe bellows reaches a maximum suicient to pull the trigger and discharge the.

ing movement, a pin provided at the distal end of the said bar and adapted to be placed in abutting relation to the trigger of the iirearm, a bellows having a rod articulated to the said lever and adapted to turn the lever in a direction opposite to the said spring-urged direction, a source of air pressure, an inlet valve leading to the said source, an exhaust outlet valve leading to the atmosphere, a common gang control for thel said two( valves, pipe means connecting each of the said two valves to the saidbellows, a pressure gauge in the said pipe connection between'the bellows" and the said exhaust outlet valve, and a shut-'ofi valve in the said pipe connection betweenthe bellows andthe said inlet valve, the saidl shut-off valve being provided with a piston rod articulated to the said lever adapted, when the"pressu`reiin the bellows reaches a maximum sufficient to pull the trigger anddischarge the rearm, to close the said shut-'off valve whereby the said gauge will remain at' the said maximum reading after ythe said discharge of the rearm.

v3, In a device for measuring the trigger-pull of firearms, the combination of means for holding the firearm, a lever pivotally mounted at one end, a bar articulatedrto the distal end of the said lever and mounted 'for an extent of sliding movement, a p in provided at the distal end of the said bar and adapted to be placed inabutting relation to the trigger of the firearm, a bellows having a rod articulated to the said lever, a source of air pressure, an inlet valve leading to the said source, an exhaust outlet valve leading to the A atmosphere, a common gang control for the said two valves, pipe means connecting each of the sais two'vaivesto the said bellows, a pressure gauge' in the said pipe connection between the bellows and the said exhaust outlet valve, and a shut-oli?V valve in the saidpipe connection betWri the bellows and the lSaid inlet Valve, the said shut-off valve being provided with a vpiston rod articulated to the said lever adapted when the pressure in the bellows reaches a maximum suillcient to pull the trigger and discharge the iirearm, to close the said shut-off valve whereby the said gauge will remain at the said maximum reading after the said discharge of the rearm.

.4. In a device for measuring the trigger pull of fire arms, the combination with means for holding the fire arm, a lever pivotally mounted at one end and a bar articulated to the free end of said lever and mounted for an extent of movement, a pin at the forward end of the bar and adapted to be placed in abutting engagement with the trigger of the iire arm, a pneumatic circuit for moving said lever including an air tight chamber having a bellows therein having operaltive connections with said lever to move the same,

re'arnis,` means for holding therearm, means includinga lever for moving the trigger of said re arm, a pneumatic circuit having operative connections with saidlever-to movethesame, a pressure gage in said circuit, a shut-off valve operated by` said lever upon the discharge of the fire arm, said .shut-off valve being located between the pressure gage and the air supply whereby upon the operation of4 said` valve the pressure in the v pneumatic circuit will be maintained to. preserve the maximum gagereading. l

6. A device for measuring the trigger pull of a 're Aarm comprising means for holding the re arm, a pivoted lever, a bar reciprocatedby said lever and having means adapted, for' abutting engagement with the trigger of the re arm, a

pneumatic circuit having valve controlled inletand a valvecontrolled outlet, Voperative connections between said: circuitand said. lever for moving the lever, a pressure gage in the circuit, a-

shuteoff valve between 'the air. supply and the pressure gage and operated bythe lever upon the discharge of the 're arm, .said shut-off valve 'opi erating upon the discharge of the fire arm to trap 

